Metal tempering process



2 obviously not restricted to tools.

Patented 2, 1932 JOHN WILLIAM BRANNON, OI ALSEA, OREGON METAL TEMPEBINGPROCESS 5N0 Drawing.

The invention aims to provide a new and improved process for hardeningsteel and iron of all grades with the aid of only a forge or otheradequate heater, water, and

5 an insulating or flux a cut. This agent may consist of a mixture 0powdered borax and powdered silica, owdered borax alone, or powderedsilica a one. The process will be described and claimed using theexpression in agent and such expression is to be read 'in the light ofthe above definition. ,The steps are the same whether the agent bepowdered silica alone, powdered borax alone, or a mixture of the two.The mixture preferably consists of two parts borax and one part silica.

The illustrations herein given will apply to carbon or tool steel and tomild steel and iron, and other varieties of ferrous met- 2 als may betempered in the same ways as herein explained.

The tempering of carbon or tool steel will be described in connectionwith a pre-formed tool which has been allowed to cool, but is The toolis heated to a cherry red to a suitable distance from'its point or edge,for example about three fourths of an inch or an inch back from saidpoint or edge and is then dipped into or otherwise coated with the abovementioned agent. The agent clings to the tool and the coated tool is newfurther I heated to a high cherry heat. It is then slowa ly dipped incold water to a depth of about one half inch (or any depth required bythe extent at temper required} and then quickly plunged entirely intoand withdrawn from the water. This leaves sufiicient heat in the tool todrive the temper down to the point or edge and the latter will showcolors from straw to sky blue. These colors are gener ally lznown toindicate the degree of hardnessto. which the tool has been tempered, andwhen the proper color comes to the point or edge or the tool, I againplunge the latter in Application filed August 19, 1980. Serial No.476,454.

the water. During the interval between the first and second plunges, theagent acts as an insulator and prevents too ra id cooling. The secondplunge, when following the conventional way of temperin causes trouble,for the tool will be harder back of the point or edge, but by using theinsulating agent, the highest temper is insured at the point or edge. Ithas heretofore been. proposed to use borax and the like to harden steeland iron but by my process, the borax, or other insulating agentperforms the function of preventing hardening beyond the desired zone.-When I dip the first time, I reserve enough heat to drive the temperdown to the o0 proper color and the insulating agent prevents the toolfrom cooling too quickly Then I plunge the second time and by f0 lowingthese steps, I temper to the greatest extent where needed and overcomethe unas desirable element of tempering to a greater degree behind thepoint or edge with danger of breakage.

To harden mild steel or iron, the piece to be hardened, is heated to acherry red or a re little higher and dipped into the above describedagent, the heat causing the agent to adhere to the metal. The coatedmetal is then reheated to the fusing point and cooled quickly in coldwater. The agent acts now i as a flux, causing the metal to run. Thisseals the grain or pores, solidifying the metal and producing whencooled, hard product whiph is much tougher than carbon or tool steeMachine parts, tools and ferrous members of all descriptions, may besatisfactorily tempered according to the process herein'disclosed andthe tempering may be carried out without the aid of expensive ovens,furnaces or other apparatus.

I claim A process of tempering tool steel comprising the steps ofheating the steel substantially to a cherry red, coating the heatedsteel with the herein described agent owdered borax, powdered silica, orboth), re eating the coated steel to a high cherry heat, dipfif thecoated part slowly into water to t e epth 7 required by the extent of.tempering desired, quickly lunging the steel into and removing it from516 water, watching the color changes on the steel and when-the soughtcolor appears-immersing the steel a ain in the water;

In testimony whereof I a my signature.

JOHN WILLIAM BRANNON.

